Back To The Battery Powered ATV - Two Parter

[LowGear]

1.)  I'm looking at Costco batteries that come with a one year free replacement warranty.  It's down hill from there.  
     A.)  The easy to fit batteries are rated at 700 MCA - 85 Amp Hours.
     B.)  The tight fit ones are rated at 750 MCA - 115 Amp Hours.
     C.)   Both are labeled Marine Deep Cycle.  If the machine works OK then I'll eventually upgrade to real batteries.
     D.)   What do these numbers really mean for a 36 Volt Cushman Golf Car powered Polaris ATV (diagram included) that will never be more than three blocks from home job site?
            i.)  The motor is rated at 36 volts with a draw of 53 Amps maximum.  Cushman used the same motor in their 48 volt units.  I'd almost have to put the forth battery in a back pack.

2.)  The farm has lots of uppy-downy.  1000 feet deep with a rise of around 250 feet in the first 700 feet of driveway.
      A.)  Can I make the system a braking resistant charging system?  (Putting it in Reverse with the throttle wide open while going down hill forwards?)

I've upgraded personal fun projects.  Weekends or those two days a week that I'm not on call to someone else are now dedicated to stuff I actually enjoy.  This is a radical departure from running around like a decapitated chicken the full seven days a week.  Each project must realize a major advancement - OK, something needs to happen.

Your usual thoughtful reliable advice and education is requested.

Casey

[DanG]

Some years ago and now lost in time on the internet I followed a project thread of a fellow who skipped using batteries all together on his camping-toy Golf Car. He started with one and then went with two Honda Eu2000 inverter generators through some serious battery chargers. The reduction in weight literally had the Golf Car flying near 50mph with its stiff suspension.

Forwarding the same idea to a Polaris ATV with engine replaced by the 36V motor could be a remarkable project - have the drive train perfected and swap in some battery weight for short trips w/ fuel assisted 'get-it-home' back up. As cheap as some of the little suitcase generators have become it sounds cheaper to accomplish than purchasing and installing batteries.

Regenerative braking is not easy to accomplish safely - normal friction braking has to occur and then be released when the electrics are proven active, then reapplied once speed has been slowed to where the electrics are no longer efficient. Releasing perfectly good friction brakes at high speed is a huge liability.

Surely there is an off the shelf electric-car controller out there that has the interlocks and logic designed in?

Keeping the friction brakes and the regenerative braking separate but full time on - as in anytime in throttle idle the motor is throwing charge to a resistor grid or charging batteries - would mean no coasting downhill, on flats etc. Having a separate 'new' control pushbutton or lever to feather in electric brakes when coasting might be worth the effort.

[LowGear]

Hi DanG,

No, I'm going down the batteries path.  I'm closing on this project and I'm not going to get side tracked at this time. 

Now a trailer with a DC source just might be a whole new project program - for extended missions. 

Thanks for brain food,

Casey

[uber39]

most EV controllers that have regen get their signal from the brake light switch,Kelly Controllers do a regen controller, not recommending Kelly although I do use them I don't really like them, but if you want regen their a lot cheaper then most.
        Ian

[LowGear]

Hi Ian,

I went over to Kelly.com and learned about my next upgrade.  My reply to DanG reminded me that getting the unit down and up (the tricky part) the driveway is the primary goal.

What a step up these electronic controllers represent.  Thanks for the heads up.  I was quoted "at least $400" from a dealer I get parts from and so I promptly forgot about the electronic answer to these mid twentieth century mechanicals.

I've also stopped by Buggies Gone Wild.Com and after reading have decided the more battery the better.  Reducing the weight by half doesn't justify reducing the lead by half much less by 2/3s.

Today is speed controller day.  The rotating throttle device selects voltage from the result of passing the total load through a series of three heavy springs (resisters) and picking from 0, 1/4, 1/2, and 3/4th increments.  I'm thinking either Frank (as in Frankinstien) or Abby Normal (later version) as a name after looking at this part of the system.

Casey

[SteveU.]

Hi Casey/LowGear
I was just cleaning out my down load finles and really looked at your factory wiring diagram.
As shown it would need 6 volt batteries for a 36 volt system; 8 volt batteries for a 48 volt system.
You Costco "Marine" batteries would be 12 volt.
What is your charger voltage? This is what you need to set up to. I think you already know banking with these 12 volt battries will only give you ~1/2 capacity, yes??
Is this your Buggies Gone Wild realization?
Regards
Steve Unruh

[LowGear]

Hi Steve,

Thousands of these units and sister units even from Japan run on 36 volts.  You're correct about the traditional way of setting up the batteries.  I suspect my three marine deep cycle 12 Volt 115 Amp batteries don't even make the 50% factor but I am moving a lot less weight not to forget the range expectations.  Golf cars travel a couple miles on an 18 hole afternoon while my unit won't see a mile a week.

BGW threads forced my to realize that marine grade batteries really aren't the same thing as golf car and solar application deep cycle units.  $7.50 per cell vs $33 per cell.  One of my favorite childhood mentors was actually correct.  "You get out of this life what you put into it."

The charger that came with the Cushman in about 1960 is rated for 36 volts as is the Yamaha my neighbor just picked up.  I hope it still works.

Casey

[mobile_bob]

if your charger is a 1960 be sure to check the voltage when attached to the batteries
and listen for really abnormal buzzing inside

1960 was getting close to when we see selenium rectifiers being replaced with silicon rectifiers
the old selenium degrade over time and put out some toxic smoke, so don't inhale what comes out of it if you can help it.

you just don't want an AC component leaking past and going into the batteries, besides not charging very well it is hard on the plates.

fwiw
bob g

[LowGear]

Thanks bob g,

I'm glad to see you appreciate my ignorance knowledge base.  It's so old that the case is made from .125 aluminum but I'm pretty sure it's Y2K compliant.

Casey